PLL and Amplifier [hlp]
I want to amplify the output power of a PLL by a monolithic gain block from minicircuits (GALI-51). But the GALI-51 doesn't work correctly and attenuates the power about 20dB! What's the problem?
I have designed the PLL using ROS-1700W VCO from minicircuits.
can you attach your schematic
did u used the R bias correctltly , the amp work from minimum supply of 7 V , r u sure u circuit is ok
i think the amp is not working , or damaged
khouly
Hello,
Something wrong with the bias of the amplifier?
Please attach your schematic if possible...
regards.
I am using the Gali51 on a project right now and it works fine. It sounds to me like it is either not biased properly or blown up. Are there dc blocking caps on the input and output? Are they dc open circuits, as measured on an ohmeter?
What is the dc voltage on the input pin and output pin of the chip when biased on? What is the current draw through to bias tee? If you have a spectrum anlyzer, is the chip oscillating?
Do you have a really good RF ground (multiple vias) on the chip?
Summing up earlier comments, there are 3 possible reasons for the "attenuation" behaviour.
1. The given IC is bad or demaged (perhaps because of the point 3. oscillation).
2. It does not have proper bias. (you can measure the DC parameters easily)
3. With incorrect grounding, it oscillates at some frequency (you can observe it with a spectrum analyzer. Be careful, oscillation frequency may be up to 4 -5 GHz high).
Can I use a supply of 5V, with the bias resistor for 18 Ohm in series with an inductor as a RF choke for 500kHz to 3GHz? I could not find from the datasheet that the minimum supply should be greater than 7V.